Many condensation or step-growth polymers, including polyesters, polyamides, and polycarbonates, are widely used to make plastic products such as films, bottles, and other molded products. The mechanical and physical properties of these polymers are highly dependent on their molecular weights. Much effort has been placed on developing the next generation polycondensates by increasing molecular weight and introducing branching. However, increasing molecular weight during the initial polymerization process generally requires long reaction times and high temperatures, resulting in polymer degradation, poor application performance, and poor finished part appearance. Moreover, in many cases, reactor limitations restrict the maximum molecular weights that can be achieved during the initial polymerization process thereby limiting the range of applications of such polymers. Solid state polymerization (SSP) may be used to further process the synthesized polymer and increase molecular weight. However, SSP is time consuming and expensive.
Typically, polycondensation reactions are reversible and subject to dynamic equilibrium at higher reactive group conversion and polycondensate molecular weight. Constant removal of condensation product(s) becomes necessary in order to displace equilibrium towards products thus enhancing forward reaction rates, increasing product molecular weight and reactor productivity. Operation at high temperatures and extreme vacuum conditions are necessary to eliminate condensation products from the reaction mix, to achieve higher molecular weights (or intrinsic viscosity, I.V.) in a suitable time. Given the asymptotic nature of the polycondensate molecular weight increase with reaction time, attempts to produce higher molecular weight products result in longer reaction times, decreases in reactor productivity, and added energy and labor costs. Higher molecular weights are desirable for higher product performance, yet unattainable economically with the current art. Moreover, it is known in the art that extended polymerization times lead to a variety of degradation by-products that affect the performance and appearance of these products.